Several prior patents are concerned with either eliminating or controlling the pitch of a dozer blade about the universal connection to the C-frame to avoid damaging stresses in the mounting assembly or high pressures in the angling cylinders. The prior proposed solutions to this problem have included complex relief circuitry, such as disclosed in U.S. Pat. No. 3,991,832, or complex linkages or blade support arrangements, such as disclosed in U.S. Pat. Nos. 4,083,414 and 4,424,871 and Canadian Pat. No. 1,115,514. These arrangements have not, however, proven commercially satisfactory for controlling or preventing pitch of the blade and the mounting arrangements disclosed therein are generally too complex for practical application.
Reference is also made to U.S. Pat. No. 4,201,268 of Claude M. Frisbee assigned to the assignee of the present application. This patent discloses the general arrangement of the preferred embodiment of the blade mounting assembly of this invention, but fails to recognize the need to control or prevent pitching of the dozer blade. With the arrangement disclosed in the Frisbee patent, it was possible to pitch the blade forwardly sufficiently to cause failure of the angle-pitch piston cylinders. Further, the pitch of the blade may change slowly under a constant load due to leakage in the hydraulic circuit. These problems have been eliminated by the dozer blade mounting assembly of this invention which prevents any pitching of the blade.